Insulated mounting



Nmv. 4, 1958 .M. J. ZUNICK 2,859,273

INSULATED MOUNTING Original Filed March 13. 1952 IHU.

\25 Q N u N --/7 MICHAEL J. 2%??? ATTORNEY United States PatentINSULATED MOUNTING Michael J. Zunick, Greenfield, Wis., assignor toGeneral Electric Company, a corporation of New York Original applicationMarch 13, 1952, Serial No. 276,313, now Patent No. 2,732,510, datedJanuary 24, 1956. Divided and this application June 17, 1953, Serial No.362,207

3 Claims. (Cl. 174152) The present invention relates in general toelectronics, and has more particular reference to electron emitters, theinvention pertaining especially to an improved support structure forfilaments of the sort commonly employed as electron emitting cathodes inelectron flow devices, such as X-ray generating tubes and the like. Theinvention comprises subject matter divided from a copending applicationfor United States Letters Patent, Serial No. 276,313, filed March 13,1952, in response to which U. S. Patent No. 2,732,510 was issued onJanuary 24, 1956.

X-ray generating tubes commonly comprise an anode and an electronemitting cathode element enclosed in a sealed and evacuated envelope,X-rays being generated at the anode as the result of impingement thereonof electrons emitted by the cathode element. The electron emittingelement is commonly mounted in a cathode structure embodying a cupadapted to aid in directing, toward the anode, electrons emitted by thecathode element.

An important object of the invention is to provide improved means formounting and insulating an emitter support stem in a cathode cup elementof the character mentioned; a further object being to employ a block ofsuitable insulating material sized to fit snugly in a seat formed in thecup element, the block being formed with a support channel therein andsized to snugly receive an emitter support stem in accurately mountedposition in the cup element.

Another important object is to employ a formed block of insulatingmaterial comprising magnesium oxide, lava, glass, porcelain, or thelike, for mounting an emitter support stem in a cathode cup structure; afurther important object being to provide improved means for mountingand retainingthe block of insulation in mounted position on the cathodecup element, said means comprising a shell-like housing adapted toretain the block in operative position to support and insulate anemitter carrying stem mounted therein, even though said block may becomecracked in service.

Another important object is to provide improved and simplified meanswhereby a filament support stem may be mounted-and secured in preciselyadjusted position in a stem supporting member, such as a cathode cupelement.

The foregoing and numerous other important objects, advantages, andinherent functions of the invention will become apparent as the same ismore fully understood from the following description, which, taken inconnection with the accompanying drawings, discloses preferredembodiments of the invention.

Referring to the drawings:

Fig. 1 is a diagrammatic view of an electron flow device including acathode structure embodying the present invention;

Fig. 2 is an elevation view, partially sectionalized, showing astructure embodying the invention;

Figs. 3 and 4 are sectional views taken substantially along the lines3-3 and 44 in Fig. 2; and

Fig. 5 is an enlarged sectional view through a stem insulating andsupporting device forming a part of the structure shown in Figs. 2 and3.

To illustrate the invention the drawings s'how electron emission meanscomprising a cathode structure C of a sort well adapted for use inelectron flow devices, such as an X-ray generating tube T. As shown, thetube comprises an anode A and the cathode structure C enclosed Withinand supported on a sealed and evacuated envelope E, which may be of anydesired or preferred form and construction. X-ray generating devicesoperate as such in response to impingement on the anode of electronsemitted by the cathode, such electronic impingement resulting in thegeneration of X-rays at the anode, whence the rays may be transmittedthrough and outwardly of the enclosing envelope.

Metallic filaments are commonly employed as electron emitters inelectron flow devices, such filaments being electrically excitable, forelectron emission therefrom, as by the passage of electrical currenttherethrough, from a power source located outwardly of the envelope ofthe device. Electrons emitted by an energized filament are commonlycaused to travel toward and to impinge upon the anode of the deviceunder the influence of an electron driving potential applied between thefilament and the anode, as from a suitable source of electrical poweralso disposed outwardly of the envelope. In such electron flow devices,therefore, it is necessary to provide for mounting the electron emittingfilament within the enclosing envelope and to provide for electricallyconnecting the filament not only with an external source of filamentenergizing power, but also with a suitable external power source forapplying electron driving potential between the anode and cathode of thedevice.

The present invention provides an improved mounting structure forsupporting an electron emission filament in operative position withinthe sealed envelope of an electron fiow device, structure also aifordingmeans for electrically connecting the supported filament with electricalpower sources located outwardly of the envelope of the device in whichthe structure is or may be assembled for use.

As shown in the drawings, the electron emission means of the presentinvention comprises an electron emitting filament 11 and a supportstructure 12 forv mounting the filament 11 within the sealed envelope ofan electron flow device. The support structure 12 comprises a preferablycylindrical block 13 of any suitable material, such as steel, said blockhaving an outwardly opening slot or groove 14 formed in its front end,the groove 14, in the illustrated embodiment, extending diametrally andtransversely of the block 13 and opening at the opposite sides thereof,thereby facilitating the formation of the groove by a simple millingoperation transversely across the front face of the block. The block 13may also be formed with a pair of parallel, spaced apart, preferablycylindrical channels 15 and 15', said channels each opening at one endupon the bottom of the groove 14, the opposite ends of the channelsopening into enlarged cavities 16 and 16 formed in and opening outwardlyof the rear face of the block.

The filament 11 is supported with its axis lying substantially in themedial plane of the groove 14 and at a predetermined elevation betweenthe bottom and open top of the groove, the opposite ends of the filamentbeing mechanically and electrically connected on mounting stems 17 and17, of suitable electrical conducting material such as molybdenum,supported on the block 13 in position extending coaxially with respectto the chana nels 15 and 15'. In that connection, the stems 17 and 17'may be formed with tapered end portions 18 and means, extending andsecured in the seats 16 and 16, is provided for mounting the stems 17and 17' in position on the block 13 presenting the tapered end portions18 of the stems within the channels 15 and 15, the filament 11, at theopposite ends therof, being formed with mount ing extensions 19 adaptedto be mechanically and electrically secured upon the tapered endportions 18 of the filament mounting stems.

In order to mount the filament supporting stems 17 and 17' accurately inposition extending coaxially with respect to the channels 15 and 15, tothereby accurately locate the position of the supported filament 11 inthe groove 14, the stems 17 and 17 may be received in preferablycylindrical mounting members 21 and 21' having portions adapted toextend snugly within the cavities 16 and 16, to thereby accuratelylocate the stems 17 and 17 with respect to the channels 15 and 15'. Inthe illustrated embodiment, the stem 17 is insulated from the block 13,while the stem 17 is electrically connected with the block so that thefilament 11 may be energized for electron emission by electricallyconnecting the stem 17 and the block 13 with a suitable source offilament energizing power. It is, of course, within the contemplation ofthe present invention to electrically insulate both of the stems 17 and17 from the block 13, in which case it would become necessary to providemeans for connecting both of the stems with the filament energizingpower source.

The mounting member 21 preferably comprises a cylindrical body ofinsulating material, such as magnesium oxide, lava, glass or porcelain,sized for snug interfitment at one end in the cavity 16. A retainingmember comprising a cup-shaped shell 22, having an outstandingperipheral rim 23 and formed to snugly receive the portions of theinsulating body 21 which extend outwardly in a suitable holding fixturefor the reception of the stem mountings in the sockets 16 and 16.- Thestem mounting, comprising the insulating body 21, the retaining shell22, and the stem mounting sleeve 25, may then be secured in place, as bywelding the rim 25 to the block 13; and the mounting, comprising themetal sleeve 21, may also be secured at one end in the socket 16. Theblock 13 with attached stem mountings may then be inverted and securedin a suitable holder for the assembly of the stems 17 and 17' and theemission element 11.

If desired, the element 11 may be mounted on the stems 17 and 17 beforethe same are assembled in the stem mountings. To this end, the stems 17and 17 may of the cavity 16, is provided to support the member 21 I inoperative position on the block 13, the shell being secured on the block13 in any preferred fashion and preferably by welding the rim 23 to theblock. Th insulating body 21 is formed with a channel 24 in coaxialalinement with the channel 15, and fitted with a preferably metal sleeve25 having a peened portion 26 at one end of the sleeve, said sleevebeing formed with a peripheral bead 27 medially thereof, whereby tosecure the body 21 on the sleeve 25 between the peened portion 26 andthe head 27. The sleeve 25 has an end extending outwardly of theinsulating body through an opening 28 formed in the bottom of thecup-shaped retaining member 22. The stem 17 and sleeve 25 are formed forsnug sliding interfitment of the stem within the sleeve.

The cylindrical mounting member 21 may comprise a sleeve of electricalconducting material sized to snugly fit at one end within the cavity 16and formed to snugly, yet slidingly receive the filament mounting stem17, the member 21' being secured in any suitable or preferred fashion onthe block 13.

The sleeves 21 and 25 preferably comprise metal which may readily beweldingly connected with the stems 17 and 17. The sleeve 21 and theretaining shell 22 preferably comprise metal adapted to be readilyconnected, as by welding, with the block 13. To this end, the sleeves21' and 25 and the retaining shell 22 may be made of nickel or a ferrousalloy of nickel, which is readily connectible by welding either with thesteel block 13 or with the molybdenum filament mounting stems or both.

It will be seen from the foregoing that the emission element 11 and itssupport means, including the mounting stems 17 and 17', may be readilyassembled on the block 13 with the element 11 located inprecisely-determined position in the groove 14 with minimum effort andsubstantially without requiring the .parts to be handled. To this end,the block 13 may be placed face downwardly be clamped in desired spacedrelation in a suitable holder and the element 11 attached to the stemends 18. Thereupon, the stems 17 and 17' may be applied in the stemmountings by employing the holder to aid in applying the ends of thestems 17 and 17, remote from the filament carrying ends thereof, throughthe channels 15 and 15' and into the ends of the sleeves 21' and 25. Thestems may then be axially moved in the sleeves until the ends of thestems 17 and 17', which are remote from the filament carrying endsthereof, project outwardly of the sleeves 21 and 25, the stems 17 and 17at such stage of the assembly being straight rods of sutficient lengthto allow the same to be held in the mountings with the stern ends 18projecting outwardly of the upper face of the block 13.

The holder may then be removed from the stems 17 and 17' to permit thesame to be drawn through the sleeves 21' and 25, as by gripping the endsof the stems 17 and 17' which project from the block remote ends of thesleeves 21' and 25, in order to draw the filament supporting stem ends18 into the channels 15 and 15 to thereby support the filament inaccurately determined position within the groove 14. Thereupon, thesleeves 21 and 25 may be welded upon the stem portions enclosed thereinto secure the same against axial'movement with respect to the block 13.After the welding operation, the stem 17 may be cut oif opposite theblock remote end of the mounting sleeve 21, while the stem 17 may be cutoff at a desired distance outwardly of the mounting sleeve 25 and bentto form a connection lug 29, as shown in Fig. 1, for a purposehereinafter more fully described.

Alternately, the stems 17 and 17, prior to the attachment of theemission element 11 thereon, may be applied in the stem mountings inposition with their filament mounting ends 18 projecting above oroutwardly of the front face of the block 13. The emission element 11 maythen be mounted and attached to said ends of the stems, after which thestems may be drawn axially in the sleeves 21' and 25 to the positionshown in Figs. 1 and 2, and weldingly secured in adjusted position inthe sleeves in the manner mentioned supra.

In order to mount the electron emission structure on and in an enclosingenvelope, such as the envelope of an X-ray tube, the same may besupported upon a pedestal or base 31) adapted to form a portion of theenclosing envelope. The pedestal 30, in turn, may carry a plurality ofmounting stems 31 and 32 secured thereon in spaced apart relationship,the stem 32 at least being relatively insulated electrically from theremaining stems 31. As shown, the pedestal 36 may comprise a tubularglass member having a closed end 33, forming a pinch seal in which thestems 31 and 32 are embedded, with the stem 32 and at least one of thestems 31 extending through and on opposite sides of the pinch seal. Thestems 31 extend upwardly of the base 39 andhave outwardly offsetupstanding end portions 31 remote from the base in position tosupportingly engage the block 13, while the stem 32 is provided with anoffset lug 32' in position to register and engage with the connectionlug 29 of the stem 17, when the block 13 is in position mounted on thestem portions 31'.

For the purpose of mounting the block 13 upon the stem portions 31, theblock is provided with lateral grooves 34 which, for manifacturingconvenience, may extend from one end of the block to its other end.These grooves are adapted to receive the stem portions 31' snuglytherein; and a holding collar 35 may be applied snugly about the sidesof the block 13 to hold the stem portions 31 in the grooves 34, andhence mount the block 13 upon the stems. To this end, the sleeve 35 issized to tightly fit upon the block 13; and the same may be welded uponthe block, especially at the stem portions 31', whereby to weldinglysecure the stems in the grooves 34 and to secure the sleeve 35 on thestems and on the block 13. When the block 13 is thus mounted on the stemportions 31, the attachment lug 29 will be disposed in adjacent contactwith the lug 32, and said lugs are preferably mechanically andelectrically secured together, as by welding.

It is thought that the invention and its numerous attendant advantageswill be fully understood from the foregoing description, and it isobvious that numerous changes may be made in the form, construction andarrangement of the several parts without departing from the spirit orscope of the invention, or sacrificing any of its attendant advantages,the forms herein disclosed being preferred embodiments for the purposeof illustrating the invention.

The invention is hereby claimed as follows:

1. An insulating structure for supporting the mounting stem of a cathodefilament on a metal base formed with a duct therethrough, comprising ablock of insulation formed with a channel opening at the opposite endsof the block, a cup-shaped retaining shell enclosing an end of saidblock and formed with outwardly extending portions for attachment on thebase to hold the block in posit1on with an end of its channel inahnement with the duct of the base, said shell having an opening formedin a the bottom thereof in position concentric with respect to the otherend of said channel, and a sleeve extending in said channel and havingan outwardly peened end in position for engagement with the duct facingend of the block at the duct alined end of said channel, said sleevebeing formed with a bead in position engaging the opposite end of theblock to secure the sleeve against relative axial movement in saidchannel, the sleeve having projecting portions extending outwardly ofthe block beyond said bead and being sized to snugly yet slidinglyreceive the filament carrying stem, whereby the same may be mounted inaccurately determined axially adjusted position in the sleeve.

2. An insulating structure as set forth in claim 1, wherein the sleevecomprises material readily connectible with a filament mounting stemdisposed therein, whereby to secure such stem in axially adjustedposition in the sleeve.

3. An insulating structure as set forth in claim 1, wherein the sleevecomprises metal adapted for integration with a metal filament mountingstem disposed therein to secure such stem in axially adjusted positionin the sleeve.

References Cited in the file of this patent UNITED STATES PATENTS2,089,541 Dallenbach Aug. 10, 1937 2,266,523 Waterman Dec. 16, 19412,299,750 Hull et a1. Oct. 27, 1942 2,307,561 Bailey Jan. 5, 19432,402,927 Stupakoif June 25, 1946 2,474,260 Leef June 28, 1949 2,479,872Seiden Aug. 23, 1949 2,535,708 VlaCh Dec. 6, 1950 FOREIGN PATENTS427,980 Great Britain May 3, 1935 868,638 France Oct. 13, 1941

